title: First direct measurements of behavioural responses by Cuvier's beaked whales to mid-frequency active sonar.
abstract: Most marine mammal- strandings coincident with naval sonar exercises have involved Cuvier's beaked whales (Ziphius cavirostris). We recorded animal movement and acoustic data on two tagged Ziphius and obtained the first direct measurements of behavioural responses of this species to mid-frequency active (MFA) sonar signals. Each recording included a 30-min playback (one 1.6-s simulated MFA sonar signal repeated every 25 s); one whale was also incidentally exposed to MFA sonar from distant naval exercises. Whales responded strongly to playbacks at low received levels (RLs; 89-127 dB re 1 µPa): after ceasing normal fluking and echolocation, they swam rapidly, silently away, extending both dive duration and subsequent non-foraging interval. Distant sonar exercises (78-106 dB re 1 µPa) did not elicit such responses, suggesting that context may moderate reactions. The observed responses to playback occurred at RLs well below current regulatory thresholds; equivalent responses to operational sonars could elevate stranding risk and reduce foraging efficiency.
authors.affiliation: Centre for Research into Ecological and Environmental Modelling, Scottish Oceans Institute, University of St Andrews, , St Andrews, UK.
authors.forename: Stacy L
authors.initials: SL
authors.lastname: DeRuiter
authors.forename: Brandon L
authors.initials: BL
authors.lastname: Southall
authors.forename: John
authors.initials: J
authors.lastname: Calambokidis
authors.forename: Walter M X
authors.initials: WM
authors.lastname: Zimmer
authors.forename: Dinara
authors.initials: D
authors.lastname: Sadykova
authors.forename: Erin A
authors.initials: EA
authors.lastname: Falcone
authors.forename: Ari S
authors.initials: AS
authors.lastname: Friedlaender
authors.forename: John E
authors.initials: JE
authors.lastname: Joseph
authors.forename: David
authors.initials: D
authors.lastname: Moretti
authors.forename: Gregory S
authors.initials: GS
authors.lastname: Schorr
authors.forename: Len
authors.initials: L
authors.lastname: Thomas
authors.forename: Peter L
authors.initials: PL
authors.lastname: Tyack
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D004455:Echolocation; D009622:Noise / Q000009:adverse effects*; D013550:Swimming; D014907:Whales / Q000502:physiology*
keywords: Ziphius cavirostris; acoustic disturbance; anthropogenic noise; avoidance response; mid-frequency active sonar; military